Starting kit doesn't have to be expensive, in case you don't like it. Here is what I started with and why I kept it or upgraded it;

Belt
===
I bought wide stiff nylon belt with a buckle similar to those "Wilderness Instructor" belts. This worked well but you must THREAD it through your belt loops in your pants AND thread it through your mag pouch/holsters if they are not clip on types (ie if they are belt loop types). This is generally fine and only hinders you when you get to the range and leave the range UNLESS you are at a range where the bathroom is in the public area and you are not allowed to wear holsters in that area! Then you have to unweave your gear to use the restroom/porta-potty. Ugh.

Later I discovered that there are things called "belt keepers" which are little snap/velcro loops that allow you to wear your normal belt (in the pants belt loops), then put the holster belt OVER that and use the keepers to attach the two belts together, thus securing the holster belt!

But I had already upgraded (actually a price downgrade!) to a "Voodoo Tactical Duty Belt". It's pretty fat, at 2.25" it's the max fatness that you might be able to accomodate with belt-loop gear holders (mag pouch/holster with belt loops) It cost me $10, the original belt was like $16. The new belt was a two belt system, a pretty cheap but effective inner belt was basically a long strip of velcro that you wear in your belt loops, then the outer belt had a buckle, but was also lined with the matching velcro so everything stayed in place!

Either belt works, it's just a matter of convenience, but you want a STIFF belt so that your holster and mag pouches don't move when you draw from them!

Holster
=====
USPSA rules state that the holster MUST cover the trigger guard, this makes sense.

I bought a $20 or so NYLON universal holster, it was an Uncle Mikes I think. Because it's nylon, it fits pretty much ALL of my guns, so this is a bonus. However, it rides HIGH and it made drawing from it (especially for a newb like me!) difficult, as well as re-holstering. Your arm is pulled up really awkwardly to pull the gun up out of it.

Someone on Calguns was selling a kydex Bladetech DOH (Drop Offset Holster) for my gun (CZ75 SP-01) so I jumped on it. Wow, it made a huge difference in draw speed/comfort! The gun hangs low like a gun slingers (NOTE: I don't think that's legal for IDPA, but great for IPSC/USPSA) and it's right near hand level, and the draw is fast out of the kydex because the retention is where the holster just pinches the front of the trigger gaurd, once you've popped out of that, the gun is fast to present.

I also have a Bladetech "Revolution" holster, which is plastic, but not molded kydex, it seems nice, but the retention is "harder" so I don't think it will draw as fast.

Anyway... This was a splurge, even from a CalGunner, it cost me $50. For a beginner, the nylon is GREAT because it will carry many different guns and you can use it until you figure out which gun you might/might not want to use in a match. It's cheap enough and it is probably IDPA compliant. It's not that fast to draw and a touch high BUT the draw is only a small part of the game. For a newbie, it's great until you figure out what you might want to specialize with and it can be used with pretty much any gun so it's still useful!

Mag Pouches
========

You'll see a lot of guys with cool kydex mag pouches, they are awesome ... and expensive unless you want to try your hand at kydex molding.

I started with "Tru-Spec" nylon double mag pouches. They have snap down flaps. The flaps are TERRIBLE for USPSA (not sure about IDPA). My mags are a touch too long for the flaps anyway, but you DO NOT WANT FLAPS on a match mag pouch. It took me about 6 matches before I decided .... OK, I'll cut the flaps off. I bought some "fray stopper" adhesive from Walmart's craft section to seal the flap stumps. This works really well. The nylon really lets the mags slide out. For my 1911, I shove cardboard spacers (ghetto!) so that the skinny mags fit in there.

So I have not upgraded from my sawed-off nylon mag holders..because they cost like $10 for the double mag holder, and I have 3 of them, so I can carry 6 mags on my belt. For kydex, you are looking at $20 PER SINGLE mag holder, that's like $120 versus $30. I will eventually make my own from kydex I think.
Anyway, for a newbie...seriously, consider buying something like what I did and chopping off the flaps OR use cheap mag holders at first. Upgrade later!

Belt loop vs clips
==========

If you buy belt loop equipment, you have to slide it on your belt, so make sure the loop size matches the belt width! My stuff by pure chance fits on my fat 2.25" belt.

If you don't use the double belt (or the belt and keepers) then belt loop equipment will drive you mad because you have to thread the belt into your pants AND the equipment AND it might not let you put the stuff where you want due to conflict of belt loop and equipment loop positions!

Belt loop stuff won't move of fall off your belt.

Clip equipment is of course much easier to put on the belt whether the belt is threaded through your pants or otherwise. It's easier to position it too. Make sure, however, that if you draw your gun or your mags, that the holster/pouch doesn't come off the belt with it!

Some clips, like bladetech Tek-Lok clamps onto the belt and will not come off when you draw.

That's what I started and upgraded to, in terms of basic equipment. As for more personal equipment, I upgraded my eye-glasses + safety glasses to an integrated prescription safety glasses pair (ESS Supressors). I bought some cargo pants to imitate "tactical pants", they are great (Lee Wrangler cargo pants!) because the cargo pocket good for a spare magazine or rag). I bought reasonably priced baseball cleats so I wouldn't slip when running around with a loaded gun! I bought a giant range bag (Midway large competition bag) and a fold up wagon to haul my giant bag around. Oh, and I bought a folding chair with an umbrella. Most of that last stuff is "Old man" stuff because I'd bring a rocking chair to a match if I could...there is a lot of waiting time!

Oh yeah, bring work gloves, you'll have to help reset each stage after a shooter and stages with steel targets or props with steel cables can get rough on your hands, especially once people start shooting and fraying the steel cables!

Eventually I'll buy some cools tactical aerodynamic shirt, but I'm not nearly good enough to rate anything more than a golf shirt!

So that's my 2 cents on starter equipment, what I like/didn't like and why I might have upgraded some of it. I hope this helps other newbies!

Oh one other thing ... take any match safety class before your first match, there are safety rules that you MUST follow or you'll go home without firing shot (but after paying your match fee). Always listen to the RO and ASK FOR CLARIFICATION if you didn't hear something or don't understand something. Your score is irrelevant for the first few matches, those are your learning matches. Do everything in slow motion. Your objective for the first matches are to NOT GET DISQUALIFIED. Forget the score, you will be near the bottom so nevermind it, you will be shooting with guys who've been doing it for years. Do it to learn and get fast/accurate LATER once all the safety stuff is DRILLED into your head and second nature.